Toxic minerals and acids at dangerous level

Millions of litres of highly toxic and acidic water will flow out of Johannesburg’s mines and swamp the city over the next two years, causing structural damage to buildings and severely affecting residents’ health.

Johannesburg. Toxic water will eat away at the city's steel foundations

Scientists predict that if drastic steps are not immediately taken to plug disused mine shafts and pump out the acid mine drainage, the poisonous water will flow into rivers and low-lying areas in the country’s most populous city at a rate of up to 70 megalitres a day – as much as 1400 average-sized swimming pools.

A joint report of the departments of water affairs, mineral resources and environmental affairs, dated March 2009, was commissioned by water affairs director-general Pam Yako after concerns raised by activist group Federation for a Sustainable Environment. It says the grave acid mine drainage situation in Gauteng:

– Poses a potentially “catastrophic” threat to Johannesburg residents. The toxic water will eat away at steel in the foundations of buildings in the city;
– Threatens to “potentially destroy the Cradle of Humankind” world heritage site; and
– As the acidic, polluted water contains heavy metals and salts, it will “pose a risk to human health … while also having a significant negative impact on the economy.

Mariette Liefferink, chief executive of the Federation for a Sustainable Environment, said long-term exposure to drinking water contaminated with acid mine drainage leads to increased rates of cancer, decreased brain function, and skin lesions.

Scientists say the toxic water will wreak havoc with the city’s water supply and affect farming along the Vaal River.

At the time the report was finalised, acid mine drainage levels stood at 900m below ground. Now, experts believe that it is less than 800m and rising at a rate of 15m a month.

Acid mine drainage levels used to be maintained by East Rand Proprietary Mines, which used to pump off and treat the toxic water from its southwest vertical shaft in Boksburg, on the East Rand. However, the company stopped pumping in 2008 after it was liquidated.

ERPM spokesman James Duncan said: “Pumping closed because the mine closed. ERPM had been in financial difficulty for some time.”

Now all those living above Gauteng’s Central Mining Basin – which stretches from Germiston in the east to Roodepoort in the west – will have to pay the price.

Professor Anthony Turton, of the University of the Free State’s Centre for Environmental Management, said the toxic water “will hit Johannesburg by January 2012. “This will be if we don’t have unforeseen rain. If we have more rain like we had in the past months, it will come sooner. It will flow out into the rivers,” he said.

Professor Terence McCarthy, of the geochemistry department of Wits University agreed: “It is probably rising faster now because of the rains we recently had. It is rising at about 15m a month, and it will leak across the full length of the Central Basin.”

The Central Basin is just one section of the Witwatersrand Gold Fields. Others include the Eastern Basin situated in the Springs area, the West Rand Basin around Krugersdorp, and the Far Western Basin around Carletonville and Randfontein. Mines in the Western Basin are already leaking acid mine drainage into rivers.

However, the report says that overflow from the Central Basin poses the greatest risk as it will threaten the “structural integrity” of Johannesburg’s buildings.

Structural engineer Professor Alakendra Roychoudhury, of Stellenbosch University, said there was a “strong likelihood” that buildings will eventually collapse.

“Acid is corrosive. All buildings with limestone in them will be in trouble. The subsurface underneath Johannesburg is limestone. There is a bigger chance that the subsurface will dissolve. Sinkholes will appear and the buildings will sink,” he said. “Steel structures will be affected, creating structural problems.”

Department of water affairs spokeswoman Linda Page said government and mining companies agreed on a public-private partnership to deal with the crisis.

The partnership will focus on pumping the water to a central point, developing new infrastructure and refurbishing that which already exists to collect and treat the water.

“The department acknowledges the seriousness of the threat … and is mindful of the urgency with which the matter has to be addressed. Once the proposed model has been signed off by all stakeholders, the feasibility study will commence,” said Page.

In the meantime, measures will be put in place to stop the toxic water from draining from the Western into the Central Basin.

“The issue is further complicated by the fact that some of the mines in the affected area are no longer operational or are ownerless, making it difficult to enforce compliance,” she said. “This requires that the state takes liability in the interest of the public, especially when the matter has to be dealt with as a matter of urgency.”

Jeremy Michaels, spokesman for the department of mineral resources, said: “The department is well aware of the serious nature and the scale of the problem of the surface and underground mine water quality and volumes in Gauteng, and has been working closely with the relevant government departments to address the issue.”